Since liquid crystal displays (LCD) feature low radiation, small volume, small weight and low power consumption, they gradually replaced traditional cathode ray tube (CRT) displays and are widely applied in desktop computers, notebook computers, personal digital assistants (PDA), cellphones and TVs.
A prior art liquid crystal display mainly includes a liquid crystal module and a backlight module. Since the liquid crystal does not emit light itself, it needs the backlight module inside the liquid crystal display for providing a backlight source for it. The backlight module directs light emitted from the backlight source uniformly into the liquid crystal panel via an optical structure film to display images. As a display device, display brightness is a main performance parameter for the liquid crystal display.
While a liquid crystal display is in use, light intensity of the external environment in which it locates would vary. In order to satisfy display brightness requirements in different situations, it is necessary to adjust backlight brightness of the liquid crystal display in time depending on the intensity of external environment light, for the purpose of adjusting display brightness of the liquid crystal display. For example, in case of weak external environmental light, it is necessary to adjust the backlight brightness to low state, and in turn to reduce its display brightness to achieve the purpose of reduced electric energy loss. However, the display brightness of operation state of the prior art liquid crystal display is fixedly set, and the display brightness of the liquid crystal display is kept in a highly bright state regardless of the light intensity of external environment. It is impossible to automatically adjust its display brightness according to light intensity of external environment, while such high brightness display of the liquid crystal display could cause waste of electric energy.
In summary, with prior art liquid crystal displays, it is impossible to automatically adjust display brightness according to light intensity of external environment when light intensity in external environment in which they locate varies, hence resulting in waste of electric energy.